COMMERCIAL APCH CHARTS AND FMC ENCOURAGE DSCNT BELOW NOISE ABATEMENT ALT.

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DURING A NIGHT VFR APCH TO TORONTO; RWY 06L; WE WERE CLRED TO 3000 FT. SHORTLY AFTER LEVELOFF; WE WERE CLRED FOR THE ILS TO RWY 06L. A QUICK LOOK AT THE APCH PLATE AND THE FMS VERIFIED THAT WE COULD DSND TO 2000 FT. WE BEGAN A DSCNT FROM 3000 FT TO 2000 FT SHORTLY AFTER PASSING DULPA WAITING FOR GS INTERCEPT. TWR CALLED US AND ADVISED US NOT TO DSND ANY FURTHER UNTIL GS INTERCEPT. THIS PUZZLED US; BUT UPON REVIEW OF THE YYZ NOISE ABATEMENT PROCS PAGE 10-4A; WE FOUND A ONE LINE COMMENT WHICH ADVISES NOT TO DSND BELOW 3000 FT UNTIL ESTABLISHED ON THE GS. I FEEL THAT IF THE TWR DOES NOT WANT ACFT TO DSND BELOW 3000 FT; THEY SHOULD EITHER HAVE THE GS INTERCEPT ALT CHANGED ON ALL OF THE APCHS AND/OR HAVE APCH CTL CLR ACFT FOR THE ILS AT OR ABOVE 3000 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS AN FO ON THE B757. HE HAS RECEIVED A REPLY FROM HIS ACR AGREEING WITH HIM ON HIS DECISION TO DSND TO 2000 FT AS DEPICTED ON THE COMMERCIAL YYZ 11-3 CHART. THE ACR HAS RECEIVED RPTS FROM OTHER CREWPERSONS THAT HAVE MADE THE SAME MISTAKE. THE FMC SHOWS 2000 FT FOR THIS SEGMENT OF FLT. THE ATCT LCL CTLR DID NOT SEEM UPSET OR SURPRISED WITH THIS MISTAKE. THE RPTR BELIEVES THAT AN INSTRUCTION BY TRACON APCH CTLR OR ATCT LCL CTLR TO MAINTAIN 3000 FT UNTIL GS INTERCEPT WOULD SOLVE THE PROB. THE RPTR HAS HEARD NOTHING FURTHER FROM THE FAA ON THIS MATTER.